What exactly is meant by alternation of generations?
Alternation of generations, also called metagenesis or heterogenesis, in biology, the alternation of a sexual phase and an asexual phase in the life cycle of an organism. The two phases, or generations, are often morphologically, and sometimes chromosomally, distinct.
Where is metagenesis found?
These species are characterised by their ability to exhibit both the stages of polyp and medusa as a part of their life cycle. As polyp represents the asexual form while the medulla represents the sexual form, it is quite evident that the metagenesis is common in Obelia.
What is Heteromorphic alternation of generation?
Pronunciation: Etymology: Heteromorphic alternation of generation occurs in organisms in which the haploid gametophyte phase and diploid sporophyte phase are different in form.
What is Metagenesis with example?
The definition of metagenesis is the reproduction cycle of an organism that alternates between sexual and asexual generations. An example of metagenesis is the reproduction cycle of a cnidarian.
Which is an example of alternation of generations?
The fern is an example of alternation of generations, in which both a multicellular diploid organism and a multicellular haploid organism occur and give rise to the other. The large, leafy fern is the diploid organism. On the undersurface of its fronds or leaves, its cells undergo meiosis to create haploid cells.
What are the two examples of bryophytes?
Hornworts, liverworts, and mosses are all examples of bryophytes. These plants are an important structural component of many damp habitats.
What is metagenesis with example?
What is Coelenterate metagenesis?
Metagenesis Introduction Alternation of generation is also known as metagenesis. It is a phenomenon whereby, in the life history of an organism, a diploid asexual phase and a haploid sexual phase regularly alternate with each other.
What is metagenesis Class 11 example?
Metagenesis is referred to the phenomenon of alternation of generation shown by cnidarians which exhibit both forms- polyps and medusae . Polyps produce medusae asexually and medusae form the polyps sexually (e.g., Obelia).
How does the life cycle of a bryophyte work?
The life cycle of Bryophytes is like all the other land plants (embryophytes) with alternation of generations. A haploid gametophyte cell contains a fixed number of unpaired chromosomes. It gives rise to diploid sporophyte, which however contains twice the number of paired chromosomes.
Which is an example of metagenesis in a plant?
For example, metagenesis shown by cnidarian Obelia has two alternate generations (hydroid and medusoid phases) where the polyp produces medusa asexually and medusa produces polyp sexually. Metagenesis occurs in some plants ( bryophytes) as well. In mosses and ferns, two alternate sexual and asexual generations are present.
What does Bryophyta stand for in plant category?
Bryophyta, the division of green plants, refers to embryophytes which in literal terms, are land plants, especially the non-vascular ones. This division includes-
What is the difference between metamorphosis and metagenesis?
Metagenesis is defined as the alternation of sexual and asexual generations of an organism within the life cycle. Metamorphosis is defined as the process in which organism shows distinct structural forms or different structural stages from adult organisms during the normal development.